There is hardware calibration available for Linux, if you can find the hardware to do so. The Sp*der 1 and 2 are allegedly supported. The Sp*der 3 maybe.
Here is an article on using the Pantone Huey (another inexpensive device that is actually supported on Linux). The X-Rite Eye-One Display is also supposedly supported, but can find no instructive links, though this one is positive.
This topic is not simple and cannot be summarized in a single posting easily. Here are a couple of useful links on hardware calibration with the Sp*der and ArgyllCMS.
The Linux Photography blog also has this article on dispcalGUI here.
ls takes it color settings from the environment variable LS_COLORS. dircolors is merely a convenient way to generate this environment variable. To have this environment variable take effect system-wide, put it in your shell's startup file.
For bash, you'd put this in /etc/profile:
# `dircolors` prints out `LS_COLORS='...'; export LS_COLORS`, so eval'ing
# $(dircolors) effectively sets the LS_COLORS environment variable.
eval "$(dircolors /etc/DIR_COLORS)"
For zsh, you'd either put it in /etc/zshrc or arrange for zsh to read /etc/profile on startup. Your distribution might have zsh do that already. I just bring this up to point out that setting dircolors for truly everybody depends on the shell they use.
As for where dircolors gets its settings from, when you don't specify a file it just uses some builtin defaults.
You can use xterm's 256 color escape codes in your dircolors file, but be aware that they'll only work for xterm compatible terminals. They won't work on the Linux text console, for example.
The format for 256 color escape codes is 38;5;colorN for foreground colors and 48;5;colorN for background colors. So for example:
.mp3 38;5;160 # Set fg color to color 160
.flac 48;5;240 # Set bg color to color 240
.ogg 38;5;160;48;5;240 # Set fg color 160 *and* bg color 240.
.wav 01;04;05;38;5;160;48;5;240 # Pure madness: make bold (01), underlined (04), blink (05), fg color 160, and bg color 240!
Best Answer
Use W (capital w) to save the top configuration after you made your changes.